The present invention is in the field of dental impression material handling systems.
Dental reconstruction and cosmetic surgery often required the repair of human teeth. In order to help facilitate this repair, models of a patient""s teeth and gums are made so that accurate repair pieces can be made. The models of teeth and gums are typically made by making a mold of the patient""s mouth. A tray having a xe2x80x9cUxe2x80x9d shaped cross section is connected via tubes to an impression material injection system. The tray is placed in the patient""s mouth and impression material is injected through the tube into the tray until the teeth and gums are surrounded. After the impression material hardens the tray is removed from the patient""s mouth forming a mold of the patient""s mouth. The hardened mold is then used to make a positive of the patient""s mouth.
The impression material is typically stored as two separate flowable components which are mixed together just before being injected into the dental tray. After mixing, the impression material has a working time during which the mixture remains a flowable material and can be manipulated and a set time after which the impression material polymerizes or rubberizes. The time after the impression material is mixed is monitored so that adjustments to the tray and impression material are not made after the working time has expired. The impression material polymerizes or rubberizes and after the set time has elapsed the tray can be removed from the patient""s mouth.
The impression material may be a silicone or any other suitable material. The working time, set time and viscosity are characteristics of the impression material that are specified in literature supplied by the manufacturer. The working time is typically 1.5 to 2.5 minutes and the set time is 2.25 to 5 minutes. Dental impression material is currently available in either cartridge or pouch dispensers of various standard volumes, including: 25, 50 and 75 milliliters.
A number of systems have been developed for handling impression material. U.S. Pat. No. 4,472,141 discloses several mechanical devices including: levers, ratchets and gears/screws which drive a plunger into a barrel which may contain a dental impression material. The use of these mechanical devices applied to dental impression applications is problematic because the flow of impression material is a function of the force exerted by the operator. It may be difficult for the operator to regulate the mechanical device force so that an even flow of material is produced.
Electric motors may be used to extrude impression material from a dispenser. Westone Laboratories and Dispensing Technologies International sell devices having an electric motor which rotates a gear mechanism which drives a piston into the dispenser to extrude impression material. A manual switch controls the motor and movement of the piston and the flow of impression material from the dispenser.
Pressurized gas systems have also been developed for the extrusion of dental impression material. U.S. Pat. No. 5,370,533 discloses a mechanism which uses pressurized gas to move a piston and drive a rod into a dispenser which extrudes impression material through a tube to a dental tray. Pressurized gas systems can be large heavy floor mounted systems which are connected to the dental tray with a long tube. The time required for the impression material to flow through the tube to the dental tray reduces the available working time of the impression material.
A problem with viscous material extrusion devices is that the working and set times must be monitored by a separate timer or clock. What is needed is a system that incorporates a timer to keep track of the working and set times of the material immediately after the components are mixed. What is also needed is a compact light weight system which can be placed close to the tray so that the viscous material can be delivered to the tray without travelling through a long tube which consumes the working time wastes.
The present invention is a light weight portable impression material dispensing system used to inject impression material into dental trays to make molds of a patient""s mouth. The inventive system utilizes pressurized gas to move one or more pneumatic cylinders which drive two rods into a two cylinder dispenser. Each cylinder of the dispenser contains a different material component. The two material components are mixed and extruded through a tube connected to a dental tray. A timer incorporated into the inventive system monitors the time after the material components have been mixed and inform the operator of the remaining working time and set time of the material. In one embodiment, switches used to control the flow of material are mounted in a hand grip attached to the injection system so that the entire system is held and controlled by one hand. In another embodiment, the system is a table top unit which is also controlled with one hand.